Rheostat



E. M. BENTLEY. RHEOSTAT.

APPLICATION FILED JULY 11. 919.

1,41 1,901, Patented Apr. 4, 1922.

Y Fly- "cause STATES EDWARD M. BENTLEY, Oli LAWRENCE, NEW' YORK.

nHnos rAr.

S eeification of Letters Patent.

Patented Apr; 4, 1922.

Application filed July 17, 1919. Serial No. 311,525.

To all whom it may] ccwf-crnr Be it known that I, Eowann M. Ban r, a citizen of the United States, residing at Lawrence, county of Nassauyand State of New York, have invented certain new and useful Improvements in Rheostats, the following being a full, clear, and exact disclosure of the one form of my invention which I at present deem preferable.

Fora detailed description of the present form of my invention, reference may be had to the following specification and to the accompanying drawings, which illustrate my invention, wherein Fig. 1 is a diagrammatic side elevation of my rheostat;

Figs. 2 and 3 are respectively edge view and plan view of the resistance ribbon as it is cut from the sheet and I I Fig. 4; shows it foldedinto loops; Figs. 5 to 8 show the mode of applying thestrip to the loop bar; 1

Fig. 9 showsthe mode of securing'the loop tip to the 'presser plate;

Figs. 10 and 11 show the circuit breaker. My invention relates to a development of the rheostat shown in Letters Patent No.

1,313,853, granted to me August 19, 1919, wherein a resistance conductor is extended in one or more loops that are progressively closed or opened to vary the resistance. In one form the resistance conductor is a ribbon, the tip of each loop being connected to the upper or lower edge of a presser plate which is pivoted at its side edges by trunnions and has its surfaces curved or arched. The opposite ends of the loops are anchored to a loop bar parallel to the axis of the plate which is acted on by springs that draw the loops taut. At the loop bar the incoming end of one ribbon of a loop is ofiset on the bar to form the outgoing end of the next ad jacent loop. By this means the two ribbons of a loop arebrought face to face and can be brought into contact with each other by the presser plate. The loops extend as tangents to the curve of the arched face of the presser plate, so that, by a slight oscillation of t 1e plate, the loops are progressively opened or closed as they bend over its curved face. I now purpose to form the loops by cutting them from a sheet of resistance material and also to increase the conductivity of the loops towards their divergent ends by increasing the thickness of the material of which they are composed; This gives increased carrying capacity as the resistance is reduced and the current increased, while by varying the thickness instead of the width of the ribbon, the gain in carrying capacity does not involve any loss in presser-p'late area.

Referring to Figs. 2 and 3 of the drawing, I take a sheet of resistance material. and cut therein narrow parallel slots which start from opposite edges of the sheet alternatel but donot extend clear across the sheet. hi. divides the sheet into narrow ribbons connected in series by the offset portions at'the alternate ends as is shown clearly in Fig. 3. A sheet cut in this manner is then folded-over at the middle along the line -a;-a as appears in Fig. a. It is evident that the ribbon is now formed into a set of parallel loops having their opposite sides face to face and connected in series. t only remains to stretch these ribbon loops between the loop bar on the one hand and theedge of the presser plate on the other hand. For this purpose'theloop bar 13, which is a thin strip of insulation, is formed with lugs C, CC on its top and bottom faces alternately and properly spaced. Over these lugs C, C are hooked the ends of the loops as shown in Figs. 5 to 8, the rear edges of the lugs being undercut to give a hooking effect. In-- stead of the lugs the ribbon may be merely tacked to the loop-bar. By this arrangement the ribbon is not passed around the bar but applied to the top and bottom sides thereof alternately. their tip ends the two sides of a loop are bent over the edge of the presser and secured by a hook passing through a small hole in the doubled end as shown in Fig. 9. Thus the loops can be secured in operating position by merely hooking them on the loop-bar and the presser and when drawn taut will be held permanently in place. In Figs. 10 and 11 I have shown a means for finally breaking the circuit, it being remembered that when a loop is fully open and its resistance all in circuit, its converging extremity still remains closed. To then break the circuit I provide an external switch,'operated by the same -means thatoperatcs the presser, but remaining closed until the loop is fully opened; then a further movement opens the switch and breaks the circuit.

What I claim as new and desire to secure by Letters Patent is:

1. A rheostat formed of a sheet of resistance material cut longitudinally and folded to form a series of loops, and a presser con neeting the opposite sides ot the loops progressively beginning at the closed end. of each loop.

2. The mode of manufacturing a ribbon rheostat which consists in cutting a sheet of resistance material along parallel lines, tolding it to form a series of ribbon loops and mounting it on suitable supports.

The mode of manufacturing a ribbon rheostat which consists in cutting a sheet of resistance material along parallel lines with oli'sets at intervals, -li'olding the sheet to form a. series of loops and mounting it on a suitable support.

l. The mode of manufacturing a ribbon rheo tat which consists in cutting a sheet of resistance material having a tapering thicle ness along parallel lines to form a series of loops tapering in thickness towards their closed ends.

The mode of manufacturing a ribbon rheostat which consists in cutting the ribbon from a sheet of varying thicknes to locally adjust its conductivity anddmouming it on a suitable support.

6. A rheostat'lormed oi a ribbon folded into a series of loops and of varying thickness in each loop.

7. A rheostat formed of a conductor arranged in a series of loops and of increasing thickness from the closed end of each loop.

8. A rheostat comprising a conductor formed in a series of ribbon loops, a presscr bringing the sides of the loops into electrical connection progressively beginning at the closed ends of the loops, and a switch operating with the presser for opening the circuit through the loops after they have been opened by the presser.

9. A rheostat comprising a loop of conducting material, a presser "for bringing the sides of the loop into contact progressively beginning at the closed end of the loop, and a switch operating with the presser to open the circuit through the 1001) when the said loop has been opened by the presser.

10. A rheostat comprising a series of ribbon loops with an offset connection between succeeding loops, an oscillating presser acting to connect the opposite sides of the loops progressively along a curved contact surface, a switch in the circuit containing the loops, and an. operating connection between said presser and the switch.

11. A rheostat comprising a plurality ol. loops connected in series by alternately disposed ollsets, a loop-bar secured. between the divergent ends of said loops, and means for progressively opening and closing the loops.

12. A rheostat having its resistance "formed of a sheet cut along parallel lines and folded transversely of the cuts to produce a series of consecutive loops.

Signed at New York city, county and State of New York, this 11th day of. July,

EDlVARD M. BENTljl li" 

